Notation for electrolytes

On the other hand, this equation does not apply to the dissociation of a species which is itself an ion. For example, it does not apply to the process jjgQ  

The dissociation of electrolytes is evidently a particular case of reaction equilibrium in solution. Electrolytes are conventionally divided into the classes weak and strong according to whether the degree of dissociation is small or very large respectively. However, this distinction will not be made except where it is useful and most of the following discussion will be entirely general in character. 

The chemical potentials, etc., of the positive and negative ions and the undissociated part of the electrolyte will be denoted by the subscripts +, — and u respectively. The subscript 0 will be applied to the solvent. For simplicity the discussion will be limited to the case where there is only a single electrolyte in the solution, but the generalization to the case of mixed electrolytes may be readily carried out. 

From the stoichiometry of the dissociation as expressed by equation (10 20) we have  

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